The invention relates to a catch device for securing the passenger seat back of auto mobile seats, and more particularly, to an inertia-driven device for securing the passenger seat back in the event of a collision.
In order to facilitate passenger comfort in an automobile, it is desirable that the degree of inclination of the passenger seat back be adjustable. However, during a collision, the position of the back rest must be fixed in order to decrease the incidence and severity of whiplash injuries to the occupants. According to a prior art device (WO 98/35 850), a head restraint is fixed by an unlockable catch device. This catch device is capable of being unlocked by an adjustment mechanism. In the event of a collision, even in the case that the catch device has been unlocked by operation of the adjustment mechanism, an inertia-sensitive element slews the catch element into engagement with the catch-gear teeth of the catch device. This solution suffers from the fact that the spring that forces the catch member to engage the catch teeth must be designed to be comparatively weak so that passengers may normally easily operate the adjustment mechanism.
Taking the state of the art as a point of departure, it is an object of the present invention to create a blocking device that is quick to react and secure the catch device of a backrest, the inclination of which is adjustable.
This object is accomplished using a locking bolt attached to the seat, the bolt having a retracted position and an extended position, and having an axis coincident with the direction of bolt movement and parallel to the axis of rotation; an opposing member affixed to the seat back, the opposing member having a blocking opening disposed to receive the lock bolt when the lock bolt is in the extended position; an abutting piece affixed to the seat and having an acceptance opening, wherein the locking bolt, blocking opening, and acceptance opening are disposed coaxially, and wherein when the locking bolt is in the extended position a portion of the bolt passes through the blocking opening and thence into the acceptance opening.
This basic locking mechanism is augmented with an inertial sensitive means for extending the bolt through the blocking opening and thence into the acceptance opening. The inertial sensor may be the same means provided for deploying the airbags in the event of a collision. The means for deploying the locking bolt is a pyrotechnic device which may be similar to the pyrotechnic used to inflate the airbags in response to the inertial sensing means detecting a sudden deceleration greater than a predetermined magnitude. Functionally, pyrotechnics provide extremely rapid and certain deployment. Moreover, their safety in an automotive environment is established by the many years of service as the means of inflating airbags.
In addition means are provided for determining whether seat back is locked wherein the determining means prevent bolt-extending means from operating unless seatback is unlocked.